324 Dr Martin Barry on 



Fibre is thus more primitive even than the cell ; for fibre 

 forms the cell. It is more universal too ; for fibre, which I 

 have just stated to be but the nucleolus in another shape, does 

 not always pass into the membrane of a cell. — it forms other 

 structures without having first to form a cell.* Hence, in 

 this communication, when speaking of the " cytoblast," I 

 have frequently mentioned it as the " cytoblast" so-called ; 

 for the term is inappropriate, — this body does not always 

 become a cell. 



The two spiral filaments composing fibre, at first appeared 

 to me to run in opposite directions, which I subsequently saw 

 was not the case, — their direction is the same. This error I 

 corrected in Muller's Archiv for 1853, in a paper On Muscle, 

 which Professor Purkinje, Foreign Member of the Royal 

 Society, translated into German, and communicated to that 

 Journal, after I had convinced him of the twin spiral struc- 

 ture of the muscular fibril ; an observation first announced 

 in my paper " On Fibre," Phil. Trans. 1842. For I found 

 the muscular fibril to have a structure exactly the same as 

 that of other fibre, and to be distinguished from it mainly by 

 permanently retaining the twin spiral structure as an attri- 

 bute of its function,"]" and presenting stages of contraction 



* If all that we are in the habit of calling cells be entitled to the terra, the 

 difference in these respects, however, can be but small. For if the existence 

 of the membrane of the cell implies the previous existence of fibre, it is equally 

 certain that the existence of fibre implies the existence of the elements of cells ; 

 fibre being made up of these. (See an observation of mine recorded in my 

 paper " On Fibre" of 1842, shewing large spirals in a certain state to be made 

 up of cells ; from which it follows that the spirals of fibre, however small, are 

 composed of the elements of cells.) Yet in the order of formation fibre does 

 to a certain extent, precede the cell. For fibre may be considered fully-formed, 

 though composed of only the elements of cells ; but the formation of the cell is 

 not complete, until its membrane has arisen out of fully -formed fibre. Again, 

 although the elements of the cell are not less general than fibre (fibre being 

 composed of the elements of cells,) yet some structures are seen to consist al- 

 most entirely of fibre in which those elements have not formed cells. 



t Like all other organic fibre, however, the muscular fibril shews a tendency 

 to pass into membrane. In some instances this tendency is seen in muscle still 

 endowed with contractile power, as in the Echinodermata, where the fibrils be- 



